1. Technical Field
Invention relates generally to air actuators and more particularly to an air actuator having an elongated generally ellipsoidal shaped body formed of thin non-reinforced polyurethane sheets.
2. Background Information
Air actuators and/or air springs are well known in the art and usually comprise an elastomeric or resilient sleeve or bellows which is mounted between a pair of spaced members for maintaining the members in a predetermined spacing and/or for moving one of the members with respect to the other, or for absorbing shock exerted on one or both of the members. Air actuators move one of a pair of members by introducing a pressurized fluid, usually air, within a hollow cavity formed within the air actuator. These air actuators have various configurations and are formed of various materials, primarily a cord reinforced elastomeric material. Examples of various types of air actuators are shown in U.S. Pat. Nos. 3,982,731, 4,751,869, 4,773,519, 4,733,603, 4,819,547, and 5,506,012.
Although these prior art air actuators may be satisfactory for their intended purpose, it is desirable to be able to form an inexpensive lightweight actuator having a low profile of a relatively thin material, enabling it to expand outwardly a sufficient distance to achieve the desired movement of one of the supporting members between which it is located, not readily achievable by actuators formed of an elastomeric material, with or without reinforcing cord. Such cord reinforced construction generally increases the expense and the difficulty to produce such an actuator.
The present invention provides an air actuator having a generally elongated ellipsoidal configuration with a hollow internal cavity for receiving a pressurized fluid for expanding and contracting the actuator along its minor axis.
The air actuator of the invention is formed of at least two half members formed of sheets of a relatively thin polyurethane material which are secured together either by longitudinal welded seams, which seams extend generally parallel to the longitudinal axis of the polyurethane body, or formed of at least two elongated cup-shaped half members of thin polyurethane material by a circumferential seam.
The air actuator of the present invention includes generally rounded ends having a single air passage formed in one of the ends with an air hose connector mounted therein, preferably of the push-pull connector type, for ease of attaching an air tube therein.
Another aspect of the invention includes providing the ellipsoidal shaped polyurethane body whereby the major axis is between 1xc2xd and 5 times greater than the minor axis to provide an elongated, relatively thin configuration thereto, enabling the body to expand outwardly a short distance in the direction along the minor axis for movement of at least one of the adjacent members.
Another feature of the invention is minimizing the number of components and difficulty of constructing the pressurized air receiving body.
A further advantage of the invention is that the polyurethane body will allow maximum operating pressures of 80 psi and is able to operate within temperature ranges of between xe2x88x9230xc2x0 F. and +200xc2x0 F., and provides an actuator body less susceptible to wear.
The foregoing advantages, construction and operation of the present invention will become readily apparent from the following description and accompanying drawings.